A NEW internal war in South Sudan, now in its fifth month, has forced hundreds of thousands of people to flee their homes. When the seasonal rains begin in a matter of weeks, those in the bush, and the tens of thousands who have taken refuge inside poorly guarded UN compounds, will be without food. The UN says 3.7m people are at risk. Once again, the call has gone out for massive international aid to avert widespread death and suffering.

These unfolding events are deftly forecast by James Copnall in his new book, “A Poisonous Thorn in Our Hearts”. The author was the BBC’s correspondent in Sudan and South Sudan until 2012. Mr Copnall gives a clear-headed and compassionate account of events leading up to and after the creation of South Sudan a year earlier, and what it means for what remains of Sudan.

He places brief profiles of individuals against an historical background: a northern Sudanese farmer; a woman who supports her large family by selling glasses of tea; a musician in Juba; a writer who has criticised the rampant corruption of the former rebels now leading the country; the southern Sudanese husband forced to live apart from his northern Sudanese wife after 2011, when Sudan declared those of South Sudanese origin no longer welcome. What the author shows, over and over, are the parallels between two states that are unstable, riven by worsening ethnic divisions, deeply militarised and ruled by undemocratic elites that are corrupt, murderous and cruel.

This is a hard region to understand. The West embraced South Sudan’s liberation from Islamist northern Sudan, and many analysts still cling to a simplistic view of the differences between the two countries. Mr Copnall’s book is measured and understated. He makes considerable effort to document events accurately and to show the depth of relationships between the people of both nations.

An afterword outlines the lightning spread of ethnicised war throughout large parts of South Sudan since mid-December. Over a handful of days, hundreds of Nuer were killed in Juba after the South Sudanese president, Salva Kiir, a Dinka, claimed that his rival and former vice-president, Riek Machar, a Nuer, was planning a coup. Mr Copnall brings the book to a sorry close with the words: “Peace in both countries seems a long way off.”

Mr Copnall’s book briefly covers the economy and the role of oil, but his is predominantly a human story. Luke Patey’s book, “The New Kings of Crude”, is also about people, but these are oilmen (and women) from farther afield, chiefly China and India. Mr Patey’s research has taken him to Beijing and Delhi, where the state-owned oil companies—the China National Petroleum Corporation and India’s Oil and Natural Gas Corporation Videsh (OVL)—have their headquarters.

Like Mr Copnall, Mr Patey also has pen-portraits of individuals, though in his book they tend to be those who spearheaded and maintained exploration programmes in Sudan. Among them is China’s “old Sudan hand” Wang Shali, known as the “Iron Lady”, who went on to play a key role in Iraq; Cui Leilei, one of five Chinese oil workers who died after being kidnapped by rebels in South Kordofan in 2008; and India’s Atul Chandra, the oilman who would “reinvent” OVL.

Sudan’s civil war and American sanctions against Khartoum opened the oilfields to China and India, countries that were not troubled by Sudan’s dire human-rights record. Sudan would be their proving ground, providing crucial experience to a generation of executives and oil workers.

After the civil war ended in 2005, the oil boom finally arrived: Sudan became sub-Saharan Africa’s third-largest producer of oil. In January 2012, however, South Sudan, in a fit of pique over failing talks about the cost of shipping its oil through the north, shut down the oilfields. And now there is a new war in the south.

As Mr Patey writes, despite worsening returns and growing unease, Sudan remains the “largest overseas achievement” of the state-owned oil companies of both China and India. The “new kings of crude” may yet have a role in trying to quell the violence in the two Sudans. The West, which has struggled without apparent success for over 30 years, should welcome them.